A battery electric vehicle, or BEV, is a type of electric vehicle (EV) that uses chemical energy stored in rechargeable electric vehicle batteries (EVBs), also known as “battery packs” and “traction batteries.” BEVs use electric motors and motor controllers instead of (or in addition to) internal combustion engines for propulsion. A battery-only electric vehicle or all-electric vehicle derives all of its power from its battery packs while a pluggable hybrid electric vehicle derives part of its power from its battery packs and part of its power from an internal combustion engine.
Battery pack designs for Electric Vehicles (EVs) are complex and vary widely by manufacturer and specific application. However, they all incorporate a combination of several mechanical and electrical component systems which perform the basic required functions of the pack. Moreover, battery packs incorporate many discrete cells connected in series and parallel to achieve the total voltage and current requirements of the pack. Battery packs can contain several hundred individual cells.
To assist in manufacturing and assembly, the large stack of cells is typically grouped into smaller stacks called modules. Several of these modules will be placed into a single pack. Within each module the cells are welded together to complete the electrical path for current flow. Modules can also incorporate cooling mechanisms, temperature monitors, and other devices. In most cases, modules also allow for monitoring the voltage produced by each battery cell in the stack by a battery management system, or “BMS.” The battery pack also contains a variety of other sensors, such as temperature and current sensors, which are monitored by the BMS. BMS can also be responsible for communications with the world outside the battery pack.
There are generally a number of battery management systems in a battery electric vehicle. These systems may comprise a printed circuit board with discrete and/or integrated circuits and provide a number of sensor and communication protocols. In particular, battery management systems typically digitally communicate with a master battery controller and may communicate with other battery management systems.
Digital communication in the harsh environment of a battery electric vehicle can be problematical. For example, there may be common mode voltages in the tens of volts between various parts of the system. Since digital communication typically uses much lower voltages, the common mode voltages can be a problem. Furthermore, the battery electric vehicle environment may generate very high frequency noise, e.g. 100 MHz and above, which can disrupt the logic a BMS.
Because of the problems of differential communication in noisy environments, Manchester coding is sometimes used. However, prior art methods of decoding Manchester coded data are, themselves, prone to error due to a number of factors including oscillator mismatches between transmitting and receiving devices.